Papers by Keyword: Slip

Abstract: In the past two decades, CFRP had been used to strengthen and repair r.c. structures and recently it is also employed to strengthen historical or monumental buildings constituted by masonry structure. However, premature failure due to debonding of the FRP is one of the important issues still to be resolved. Numerous word wide research studies have dealt with the debonding problem in r.c. structures but only a few works were carried out in the masonry structures area. So, the study of the global behaviour of the reinforced masonry element seems to be very useful, both for a congruous design and to verify the strengthening strategy. To this aim, this paper summarizes the debonding phenomena between C-FRP strip and natural calcareous rock brick, employed in our buildings, by means of a testing investigation. Two different kinds of anchorage were designed and employed for the tested samples: standard and reinforced anchorage. The experimental tests carried out on the specimens permits us to compare the effective bond length, with the one obtained by International rules and especially with the Italian CNR-DT200/2004 formulation and to say that the effective bond length dictates by the rules undervalues the experimental data. The data obtained permit us also to know the shear-slip delamination curve useful for the numerical investigation, as well as both the failure mode and the "II mode" fracture energy.

Abstract: To meet the requirement of machine-made sand application in concrete structures, it is necessary to understand the bond properties of steel bar with machine-made sand concrete (MSC). Therefore, the experimental studies were carried out on the bond of plain steel bar with MSC by the central pull-out test method. Three specimens were cast as one group, 6 groups were tested considering the changes of strength grade of MSC and ordinary concrete. The bond-slip curves were measured and analyzed. The results show that the bond slip begins at the tensile side and transfers gradually to the free end before the entire slip turns up along the interface of plain steel bar and surrounded concrete, the largest average bond stress, i. e. the bond strength of plain steel bar corresponds to the initial entire slip of plain steel bar. With the increasing strength grade of MSC and ordinary concrete, the difference of slip at tensile side and free end becomes greater. Comparing that only appears in ordinary concrete with higher strength, the larger slips turn up while the bond stress reaches the largest for the plain steel bar in MSC. Larger scatter of bond strength is between specimens in the same group. Some plain steel bars yields with the beginning of entire slip along the interface.

Abstract: To avoid the fatigue fracture of casing inside slips, the plastic extension of casing cracks near slips under inner pressure after taking RTTS packer out should be analyzed. The plastic zone size of instability extension of two/three-dimensional cracks on casing was derived based on the theory of fracture mechanics. Analysis results show that hoop stress caused by inner pressure of casing is a key factor to lead to the instability extension of casing radial cracks after testing. The plastic extension zone size of cracks on casing near slips increases with the inner pressure or hoop stress. And, the plastic extension of cracks on casing near slips reduces the burst strength of casing significantly. The materials of casing materials and the inner pressure should be appropriately controlled to control the propagation of cracks.

Abstract: The HTHP completion packers slip is a key element in ensuring the reliability of the packer. It plays an important part in supporting and locking the seal bore after anchoring in the casing wall. When the slip in touch with the casing, the interaction force between them occurs, and the supporting function of slip relies mainly on the interaction with the casing. This article analyzes the depth of slip into the casing based on the theory analysis and ANSYS finite element analysis. It approves that the biting depth of the slip increases with the load, and with the increase of tooth number, biting depth is gradually reduced. At last, we get the biting depth of the slip when the packer seated, which is 0.5mm~0.7mm. Besides this, we also analyze the VONMISES stress of the slip and the casing system and find that with the increase of tooth number the tooth stress gradually reduced, and that the slip biting depth and tooth stress gradually increase with the load.

Abstract: This paper examines wide V-belt operational behaviour operated continuously variable transmission (CVT). Important for the prediction of an optimum driving performance it is necessary to understand the motion principle of the belt in the pulley during operation. First, the design of a test rig is described, where both the driving and driven pulleys are programmable controlled, giving details of the capabilities. Second, to describe the efficiency of the drive, losses due to slip and the mechanical properties of belt material are determined. To conduct the mechanical properties of the steel-reinforced belt an experimental method is introduced. Finally, emphasis is placed on determination of circumferential motion of the belt due to various drive operating parameters. Through the study, it is found that mechanical wear at both sides of the V-belt caused by the belt’s motion is the most serious problem that affects the CVT performance.

Abstract: The functional relationship is analyzed between three-phase asynchronous motor electromagnetic torque and some factors; Mechanical characteristic curve of motor performance is drawn; The inherent mechanical properties and human mechanical properties are explored in a specific application. Facts prove that mechanical characteristic analysis of three-phase asynchronous motors, to reduce the failure rate of the three-phase induction motor, to improve the running capacity and production efficiency are important.

Abstract: Composite beam takes full advantage of mechanical properties of brittle and ductile materials elements. The key point is to rely on the shear connectors ensure overall coordination of composite beam, so as to achieve the effect of flexural component. The crack in composite beam caused by brittle materials elements is not negligible. We obtained the slip of shear connectors with the second order precision under the conditions that there are cracks in the brittle material elements, and the ultimate moment is obtained too.

Abstract: The flexibility of connection between the steel plate and concrete slab gives rise to interface slip and additional deflection. A method of analysis for steel-concrete composite plate with slip effect resulting from studs is presented. The basic idea is to place a hypothetical thin shear-layer between steel and concrete slab, where all the shear deformation is concentrated in the thin layer. Analytical solutions for elastic critical buckling load of composite plate considering slip effect under axial compressive and pure shear are derived. The theory model and the solutions are then validated by means of three-dimensional finite element analysis.

Abstract: Work hardening is an important index for the evaluation of the machined surface quality in high-speed milling. The morphology of work hardening can be visually observed by the metallographic pictures of high-speed milling gained from the scanning electron microscope which includes the lattice distortion and cracks etc. Forming mechanism of lattice distortion and micro crack of micro morphology under the workpiece surface is analyzed according to the dislocation theory; meanwhile, the effects on surface quality of the microstructure of the work hardening layer are discussed, which have important guiding significances on improving the surface quality and prolonging the service life of the parts.

Abstract: Closed form solutions are derived in this work by including free end slip, relating free end and loaded end slips to bond resistance, as well as relating slip or strain at any position to free end slip. To identify the bond-slip relationship, indirect analytical identification from load-slip response curve is used. Using the identification procedure developed in this paper, very good agreement between the theoretical solutions and experimental results was observed, which validates the theoretical results derived in this work.